1. Field of the Invention
Aspects of the present invention relate to a rear suspension mounting structure for an electric vehicle.
2. Description of the Related Art
In general, a suspension system for vehicles absorbs vibration and impact transmitted from the wheels to the vehicle body during a movement of a vehicle, thus preventing damage to the vehicle body and freight caused by the vibration and impact, in addition to allowing passengers to feel comfortable. The suspension system includes a front suspension and a rear suspension.
In particular, in a four wheel drive (4WD) in-wheel electric vehicle, a rear suspension system is configured to directly transmit power to a wheel by a motor disposed within the wheel, unlike in a wheel rotating mode in which a wheel is rotated by power transmission through engine-mission-drive shaft in a gasoline or diesel automotive vehicle.
Therefore, when the in-wheel motor is employed, a power transmission device, such as differential gears, may not be provided, thereby reducing the vehicle weight and lowering an energy loss during power transmission.
FIG. 1 shows a conventional rear suspension for an electric vehicle, and FIGS. 2A and 2B shows a conventional rear suspension for a rear-wheel electric vehicle.
Referring to FIG. 1, the conventional rear suspension comprises a torsion beam 11, trailing arms 12, a spring sheet 13, a shock-absorber bracket 14 and a spindle bracket 15. The conventional rear suspension is configured such that the trailing arms 12 are directly welded to left and right ends of the torsion beam 11, and the spring sheet 13, the shock-absorber bracket 14 and the spindle bracket 15 are separately welded to the trailing arms 12. In addition, the torsion beam 11, the trailing arms 12, the spring sheet 13, the shock-absorber bracket 14 and the spindle bracket 15 are formed using steel metals.
Referring to FIGS. 2A and 2B, the conventional rear suspension for a rear-wheel electric vehicle largely includes a coupled torsion beam axle 21, a driving motor 22 and an axle assembly 23. The conventional rear suspension is configured such that the driving motor 22 is fastened to the coupled torsion beam axle 21 using bolts. Here, a housing of the driving motor 22 is fabricated using aluminum in consideration of the weight of the driving motor 22 and heat-emitting performance.
However, in the conventional rear suspension mounting structure for an electric vehicle, in order to add a driving motor to a coupled torsion beam axle, a separate fastening structure and additional space are required, which is disadvantageous in view of package utilization efficiency. In addition, the separate fastening structure and additional space increase an unsprung mass, which is disadvantageous in view of riding comfort and steering stability.
In addition, since the suspension of a torsion beam axle is basically designed to produce torsion to the central torsion beam, aluminum may be employed for the purposes of cooling the driving motor and improving packaging. In this case, however, it is difficult to achieve durability.